Diversity of Frankia in root nodules of six Morella sp. from the Cape flora of South Africa

Abstract

Africa hosts numerous endemic actinorhizal plants from the genus Morella, but the diversity of their Frankia endosymbionts has never been explored. The diversity of Frankia in root nodules collected from natural stands of six Morella species within the Cape flora of South Africa was investigated. The diversity of Frankia in root nodules collected from natural stands of six Morella species within the Cape flora of South Africa was investigated by comparative nitrogenase (nifH) gene sequence analysis. Gene sequences assigned nodular strains to both cluster I (Alnus hostinfection group) and cluster III (Elaeagnus host-infection group), with sequences from both groups recovered from three hosts: M. intergra, M. diversifolia and M. quercifolia. Cluster I sequences were found in nodules from acidic soils exclusively. Frankia strains representing both groups were isolated and characterized by 16S rRNA and nifH analysis. This study is the first to investigate the diversity of Frankia associated with endemic African actinorhizal species in their natural habitats, and to report isolation of Frankia strains from African Morella.